Digital television signal, digital television receiver, and method of processing digital television signal

ABSTRACT

A digital television (DTV) signal for use in a DTV receiver includes an extended text table (ETT) which includes a header and a message body. The header includes a table identification extension field which serves to establish uniqueness of the ETT, and the message includes an extended text message (ETM). If the ETT is an event ETT, the table ID extension field includes an event identification which specifies an identification number of an event associated with the ETT. On the other hand, if the ETT is a channel ETT, the table identification extension field includes a source identification which specifies a programming source of a virtual channel associated with the ETT. A section-filtering unit included in the DTV receiver is able to use table identification extension fields of a plurality of ETTs for section-filtering a pertinent event or channel ETT from the ETTs.

This application is a Continuation of co-pending U.S. patent applicationSer. No. 13/157,142 filed on Jun. 9, 2011, which is a Continuation ofU.S. patent application Ser. No. 12/773,745 filed on May 4, 2010, nowU.S. Pat. No. 7,984,470, which is a Continuation of U.S. patentapplication Ser. No. 11/368,458, filed on Mar. 7, 2006, now U.S. Pat.No. 7,743,397, which is a Continuation-In-Part of U.S. patentapplication Ser. No. 11/062,429, filed on Feb. 23, 2005, now U.S. Pat.No. 7,246,365, which is a Continuation of U.S. patent application Ser.No. 09/760,840, filed on Jan. 17, 2001, now U.S. Pat. No. 6,918,133.This application also claims the benefit of Korean Patent ApplicationNo. 10-2005-0108273, filed on Nov. 11, 2005, and also claims the benefitof U.S. Provisional Application No. 60/704,446, filed on Aug. 2, 2005.The disclosures of each of the above referenced applications areincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to digital broadcasting, and moreparticularly, to a digital television signal and a method and apparatusof processing a digital television signal.

2. Discussion of the Related Art

Generally, a program and system information protocol (hereinafter, PSIP)is a protocol for channel tuning and broadcast schedule transmission inATSC (advanced television systems committee) as the digital broadcastingstandard in terrestrial and cable digital broadcasting environments. Inaddition, the PSIP is a standard protocol for a transfer of tablesincluded within packets transferred by a multiplexed transport stream.

The PSIP defines many PSIP tables for the various purpose, and each PSIPtable includes one or more sections which are similar to those of theprogram and system information (PSI) tables defined by MPEG (movingpicture experts group). Each section included in a PSIP table includes aheader containing basic information of the section and a body containingthe actual data constituting the section. A broadcast receiver uses thebasic information included in headers of various sections received froma broadcast transmitter in order to select (or detect) one or morepertinent sections, and this is often referred to as section-filtering.An example of the basic information is a table identifier whichidentifies a PSIP table.

However, a certain group of PSIP tables (e.g., a group of eventinformation tables or extended text tables) have a common tableidentification. Therefore, the digital television (DTV) receiver is notable to distinguish them simply by section-filtering. In this case, theDTV receiver must parse bodies of the PSIP sections in order to detect apertinent section, and this greatly increases the signal processing timeand decreases the system's overall efficiency.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a digital televisionsignal including a PSIP table, apparatus for receiving the same andmethod thereof that substantially obviate one or more problems due tolimitations and disadvantages of the related art.

An object of the present invention is to provide a digital televisionsignal in a digital television receiver.

Another object of the present invention is to provide an apparatus fordecoding tables included in a digital television signal and methodthereof.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, adigital television (DTV) signal for use in a DTV receiver includes anevent extended text table (ETT) which includes a header and a messagebody. The header includes a table identification (ID) extension fieldwhich serves to establish uniqueness of the event ETT, and the messagebody includes an extended text message (ETM). The table ID extensionfield includes event identification which specifies a uniqueidentification number of an event associated with the event ETT.

In another aspect of the present invention, a DTV signal for use in adigital television receiver includes a channel extended text table (ETT)which includes a header and a message body. The header includes a tableidentification (ID) extension field which serves to establish uniquenessof the channel ETT, and the message body includes an extended textmessage (ETM). The table ID extension field includes sourceidentification which specifies a programming source of a virtual channelassociated with the channel ETT.

In another aspect of the present invention, a digital television (DTV)receiver includes a tuner, a demodulator, and a section-filtering unit(e.g., a demultiplexer). The tuner is tuned to receive a digitaltelevision signal, and the demodulator demodulates the digitaltelevision signal. The demodulated signal includes a plurality ofextended text tables (ETTs). Each ETT includes a header containing atable identification (ID) extension field which serves to establishuniqueness of each ETT. The section-filtering unit detects at least onepertinent ETT by section-filtering the plurality of ETTs using theirPIDs and table ID extension fields. The DTV receiver may further includea decoder which parses the pertinent ETT detected from thesection-filtering unit, and a data storage which stores an extended textmessage (ETM) included in the parsed ETT.

One condition for the operation of the section-filtering unit is suchthat the pertinent ETT has a common PID value. A first example of anadditional condition for the section-filtering operation is such that atable ID extension field included in the pertinent ETT includes aspecific (desired) or non-duplicative event identification. A secondexample of the addition condition is such that the table ID extensionfield includes a specific (desired) or non-duplicative sourceidentification.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is a diagram of a general syntax of a PSIP table associated withthe present invention;

FIG. 2 is an exemplary diagram of a bit stream syntax of channel ETTaccording to the present invention;

FIG. 3 is an exemplary diagram of a bit stream syntax of event ETTaccording to the present invention;

FIG. 4 is a block diagram of a digital television receiver to receivechannel ETT and event ETT according to the present invention;

FIG. 5 illustrates an EPG display according to one embodiment of thepresent invention;

FIG. 6 illustrates a structure of a database (DB) associated with thepresent invention;

FIG. 7 is a flowchart illustrating a method for detecting anon-duplicative channel ETT section according to the present invention;

FIG. 8 is a flowchart illustrating a method for detecting a specificchannel ETT section according to the present invention;

FIG. 9 is a flowchart illustrating a method for detecting anon-duplicative event ETT section according to the present invention;and

FIG. 10 is a flowchart illustrating a method for detecting a specificevent ETT section according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to a digital television (DTV)signal including a PSIP (Program and System Information Protocol) tableand a method and apparatus of processing a DTV signal according to thepreferred embodiments of the present invention, examples of which areillustrated in the accompanying drawings. Wherever possible, the samereference numbers will be used throughout the drawings to refer to thesame or like parts.

First of all, terminologies used in the description of the presentinvention are defined as considering functions in the present invention,which are variable according to usual practice or intentions of thosewho skilled in the art. Hence, their definitions shall be given based onthe overall contents of the present invention.

First Embodiment

The present invention relates to an ETT (extended text table) as a PSIP(Program and System Information Protocol) table included in a digitaltelevision (DTV) signal. The PSIP table is preferentially explainedprior to description of the ETT.

As the PSIP table, there is a VCT (virtual channel table) havinginformation about a virtual channel viewed by a user in a DTV receiver,an EIT (event information table) enabling an EPG (electronics programguide) service, an ETT for the EIT or the like.

The EIT contains information (titles, start times, etc) for events ondefined virtual channels. The event is, in most cases, a typical TVprogram. Up to 128 EITs may be transmitted and each of them is referredto as EIT-k, with k=0, 1, . . . , 127. And, each EIT is represented asinformation of three-hour unit. Moreover, each EIT can have informationabout at least one event.

The ETT contains extended text message (ETM) streams, which are optionaland are used to provide detailed descriptions of virtual channels(channel ETM) and events (event ETM). An ETM is a multiple string datastructure, and thus, it may represent a description in several differentlanguages.

A event ETT is mapped to each EIT. In particular, informations forevents belonging to EIT-0 to EIT-127 are recorded at ETT-0 to ETT-127,respectively. In this case, information about at least one or moreevents included in each EIT can be represented as one section. Each ofthe events has a unique event identification. And, each of the events isidentified by the corresponding event identification. And, ETM locationindicates a presence or non-presence and a location of an ETM for eachof the events.

A channel ETT is used in case that channel information having a moreextended meaning is required for n-virtual channels included in onephysical channel. In this case, each of the n-virtual channels definedin the VCT uses source identification in identifying each channelsource. In particular, if there are n-virtual channels in one physicalchannel, each of the virtual channels has a source identification. Inthis case, the source identification should have a unique value. And,ETM location defined in VCT decides whether a channel ETT exists in eachof the virtual channels. The ETM location indicates a presence ornon-presence of an ETM in each of the virtual channels and a location ofeach of the virtual channels, which is equivalent to that of the eventETT.

Each of the channel ETTs and event ETTs can be constructed with at leastone or more sections. Each of the sections includes ETM identificationidentifying the event or virtual channel and an extended text message(ETM) providing detailed descriptions of the event or virtual channel.In this case, the ETM identification is linked to event ETMidentification of a corresponding event in case of the event ETT sectionor to channel ETM identification of a corresponding virtual channel incase of the channel ETT section.

Before describing about performing section-filtering, used to filteronly non-duplicative or specific section, on each received ETT section,a structure of the ETT section will be first explained in detail. Inthis case, the section is constructed by combining data structures. Thesection starts from table identification field and ends to CRC 32 field.

FIG. 1 is a diagram of a general syntax of a PSIP table associated withthe present invention. FIG. 2 is an exemplary diagram of a bit streamsyntax of channel ETT according to the present invention, and FIG. 3 isan exemplary diagram of a bit stream syntax of event ETT according tothe present invention.

A table section of the syntax shown in FIG. 1-FIG. 3 is divided into aheader having a mutually common form, a message body recording actualdata according to the purpose of the table section, and a trailer for anerror check and correction of the table section. The header starts fromtable identification field to protocol version field. The message bodystarts from ETM identification field to extended text message field.And, the trailer is CRC 32 field.

Fields constructing the syntaxes shown in FIGS. 1 to 3 are explained asfollows. For simple and clear explanation, English expression of thesyntax is used as it is but is marked by double quotation marks.

First of all, each field constructing a header of the syntax isexplained as follows. The “table_id” field identifies the section asbelonging to an ETT and is an 8-bit field. A “section_syntax_indicator”field is set to ‘1’ and is a 1-bit field. It denotes that the sectionfollows the generic section syntax beyond the section length field. A“private_indicator” field is set to ‘1’ and is a 1-bit field. A“section_length” field is to specify the number of remaining bytes inthe section immediately following the section_length field up to the endof the section. The value of the section length field shall be no largerthan 4,093.

A “table_id_extension” field is a field associated with the presentinvention, which will be explained later. A “version_number” field is a5-bit field. For the channel ETT, the field indicates the version numberof the channel ETT. The version number shall be incremented by 1 modulo32 when any ETM in the channel ETT changes. For event ETT, the fieldindicates the version number of event ETT-i, where “i”, as in the EITcase, is the index of time span. The version number shall be incrementedby 1 modulo 32 when any ETM in the event ETT-j when “j” is not equal to“i”. The value of this field shall be identical to that of thecorresponding entry in the MGT.

A “current_next_indicator” field is a 1-bit indicator and is always setto ‘1’ for the ETT sections. The ETT sent is always currentlyapplicable. A “section_number” field is an 8-bit field and the value ofthe field shall always be ‘0x00’. A “last_section_number” field is an8-bit field and the value of the field shall always be ‘0x00’.

A “protocol_version” field is an 8-bit unsigned integer field whosefunction is to allow, in the future, this table type to carry parametersthat may be structured differently than those defined in the currentprotocol. At present, the only valid value for protocol version field iszero. Non-zero values of protocol version field may be used by a futureversion of this standard to indicate structurally different tables.

Secondly, fields of the message body are explained as follows. A“ETM_id” field is unique 32-bit identifier of this extended text message(ETM). The identifier follows a regular rule. By the rule, in case ofchannel ETM identification, source identification is written in a mostsignificant bit (MSB) b31 and two least significant bits (LSB) b1 and b0are written as ‘00’. By the rule, in case of event ETM identification,source identification is written in a most significant bit (MSB) b31,event identification is written in a bit b15, and ‘10’ is written inleast significant bits (LSB) b1 and b0. A “extended_text_message( )”field indicates the ETM in the format of a multiple string structure.

Finally, a field of the trailer is explained as follows. A “CRC_(—)32”field is a 32-bit field that contains the CRC value that ensures a zerooutput from the registers in the decoder after processing the entireTransport Stream ETT section.

As mentioned in the foregoing description, the present inventionperforms a section-filtering on the received ETT section by filteringthe header of the ETT section. For this, in the present invention, theETT table ID extension field constructing the header of the ETT is usedas followed. Namely, in case that the received ETT section is event ETT,event identification and ETM location are defined in the field to beused for the section-filtering. In case of channel ETT, sourceidentification is defined in the field to be used for thesection-filtering.

The “ETT_table_id_extension” field has a 16-bit unsigned integer valuethat serves to establish the uniqueness of each ETT instance when thetables appear in transport stream packets with common PID (packetidentification) values. The ETT table ID extension field shall be set toa value such that separate ETT instances appearing in transport streampackets with common PID values have a unique ETT table ID extensionfield value. A table type of the ETT can be previously known from MGT(master guide table) before the ETT is received. In particular, thetable type of the ETT is “0x0004” in case of channel ETT or“0x0200˜0x027F” in case of event ETT.

FIG. 2 shows a channel ETT having an ETT table type of “0x0004”. In thiscase, 16-bit source identification connecting the VCT to channel ETT iswritten in the ETT table ID extension field. And, the sourceidentification should have the same value of source identificationwritten in VCT and ETM identification. FIG. 3 shows an event ETT havingan ETT table type of “0x0200˜0x027F”. In this case, the ETT table IDextension field is a 16-bit field. A E™ location field is written in twobits of the sixteen bits and unique event identification connecting theVCT to event ETT is written in fourteen bits. In this case, the eventidentification should have the same value of an event identificationvalue of the corresponding event of EIT-k and an event identificationvalue in the ETM identification should have the same value as well.

Accordingly, in the present invention, the ETT table ID extension fieldcontains the event identification or source identification. And, bymeans of the ETT table ID extension field, the section-filtering isenabled with the header only without parsing a message body of each ofthe received ETT sections.

In doing so, by filtering the header including the ETT table IDextension field, the section-filtering can be performed in a manner thatan ETT section, which was already received and is duplicative withanother, is discarded and that a non-duplicative or specific section isreceived only.

Hence, in performing the section-filtering using the header includingthe ETT table ID extension field, the message body of each of the ETTsections needs not to be parsed and the DTV receiver receives thenon-duplicative or specific section. Therefore, by receiving anon-duplicative ETT section or a specific ETT section, a process timecan be reduced and the DTV receiver efficiency is raised.

Second Embodiment

A digital television (DTV) receiver to receive a DTV signal including anExtended Text Table (ETT) according to a second embodiment of thepresent invention is explained as follows.

FIG. 4 is a block diagram of a DTV receiver to receive channel ETT andevent ETT according to the present invention. Referring to FIG. 4, a DTVreceiver receives and processes tables according to the presentinvention and audio/video transport streams.

A tuner 10 receives a terrestrial or cable DTV signal via an antenna. Inthis case, a reception process of the tuner 10 is controlled by achannel manager 70. In particular, the tuner 10 reports a result andstrength of the DTV signal received by the DTV receiver and transfersthe DTV signal received by the receiver to a demodulator 20.

In case that a terrestrial broadcast is received, the demodulator 20performs 64-VSB (vestigial sideband) or 256-VSB demodulation. In casethat a cable broadcast is received, the demodulator 20 performs 64-QAM(quadrature amplitude modulation) or 256-QAM demodulation. And, thedemodulator 20 transfers a demodulated signal to a demultiplexer 30.

The DTV receiver shown in FIG. 4 is divided into one part performing asection-filtering on an ETT section by a header and the other partparsing the received ETT section. In this case, the section-filteringpart corresponds to the demultiplexer (DEMUX) 30 and the parsing partcorresponds to a PSI/PSIP decoder 80.

First of all, the section-filtering part is explained as follows. Thedemultiplexer 30 performs demultiplexing to filter off audio, video andPSI/PSIP tables from transport packets transferred from the demodulator20.

Demultiplexing of the PSI/PSIP tables is carried out under the controlof the PSI/PSIP decoder 80. In particular, the demultiplexer 30 checks aheader in common to the PSI/PSIP table to perform the section-filteringon the received PSI/PSIP table. And, the demultiplexer 30 generates asection of the PSI/PSIP table and then transfers it to the PSI/PSIPdecoder 80. Demultiplexing of the audio/video transport packets iscarried out under the control of the channel manager 70. In particular,if an audio/video packet ID (PID) of a corresponding virtual channel isset, the demultiplexer 30 demultiplexes an elementary stream of theaudio/video to transfer to an audio/video decoder 40.

Hence, the demultiplexer 30 performs the section-filtering on theaudio/video data, PSI/PSIP table and the like in a manner of filteringthe header only. And, data for each section generated from thesection-filtering is transferred to the corresponding decoder.

The corresponding decoder is explained as follows. The audio/videodecoder 40 decodes elementary stream packets of audio/video transferredfrom the demultiplexer 30 by MPEG2/AC3. The audio/video decoder 40synchronizes the decoded audio/video data by a VDP (video playerprocessor) and then transfers it to an output unit, i.e., an A/V & OSD(on screen display) displayer 50.

The A/V & OSD displayer 50 receives the decoded audio/video datatransferred from the audio/video decoder 40 and then displays thereceived audio/video data via screen/speaker. In this case, the A/V &OSD displayer 50 is under the control of OSD graphic data in case ofdisplaying the data via the screen.

In case that there is a key input of a viewer watching the DTV, anapplication & UI (user interface) manager 60 responds to a viewer'srequest by displaying it on the screen via a graphic user interface.

The application & UI manager 60 receives a decoded state of theaudio/video signal from the audio/video decoder 40 and then controls thedisplayer 50 via the OSD according to the received audio/video state.And, the application & UI manager 60 controls the channel manager 70 toperform channel associated management, i.e., channel map management andto manage the PSI/PSIP decoder 80. Moreover, the application & UImanager 60 stores/restores GUI control of the entire DTV receiver,user's request and a state of the DTV receiver in/from a NVRAM (or flashmemory) 90. Furthermore, the application & UI manager 60 includes thechannel manager 70. The channel manager 70 manages the channel map bycontrolling the tuner 10 and the PSI/PSIP decoder 80 to meet a channelrequest made by a viewer.

The channel manager 70 requests the PSI/PSIP decoder 80 to parse a tableassociated with a channel to be tuned and receives a report of parsingthe table from the PSI/PSIP decoder 80. The channel manager 70 updatesthe channel map according to the reported parsing result and makes adecoding request by setting the audio/video packet ID in thedemultiplexer 30.

Meanwhile, the PSI/PSIP decoder 80 corresponding to the table parsingpart is explained as follows. The PSI/PSIP decoder 80, which is a PSIand PSIP control module, performs a slave operation under the control ofthe channel manager 70. Namely, the PSI/PSIP decoder 80 sets PIDs of thePSI/PSIP tables in the demultiplexer 30. The PSI/PSIP decoder 80receives and parses the PSI section for an MPEG2 system and generates aPSI database. And, the PSI/PSIP decoder 80 receives and parses the PSIPsection for ATSC and generates a SI/PSIP database. In performing aparsing, the PSI/PSIP decoder 80 reads a rest actual section dataportion, on which the section-filtering is not performed or cannot beperformed, and then records it in the SI/PSIP database.

-   -   Third Embodiment

A method of performing a section-filtering by filtering a header of areceived ETT (Extended Text Table) section only according to anotherembodiment of the present invention is explained as follows.Specifically, in performing the section-filtering, a method of checkingand handling ETT table ID extension field included in a header of areceived ETT section is explained as follows.

An EPG (Electronic Program Guide) is preferentially explained prior tothe embodiment. FIG. 5 illustrates an EPG display according to oneembodiment of the present invention. Referring to FIG. 5, an EPGincludes VCT (Virtual Channel Table), channel ETT, EIT (EventInformation Table) and event ETT.

Information of a current date and time at a most upper end on an EPGscreen is delivered via STT (System Time Table) and exemplarily shows“Apr. 8, 2000 6:11 pm”.

A most left side “Chan” part in FIG. 5 displays channel numbers 12-1,12-2 and 12-3 of virtual channels delivered from VCT. In this case, eachof the virtual channels has source identification having a unique value.A name part follows each of the channels. The name part means a channelshort name included in each of the virtual channels and exemplarilyshows NBZ1, NBZ2 or NBZ-S. Each of the virtual channels can send achannel information message having a more extended meaning, which isforwarded via channel ETT-V for each of the virtual channels connectedto the source identification obtained from the VCT.

Although the channel 12-1 is represented as the name “NBZ1”, channel ETTconnected to the source identification of the channel does not exist. Achannel ETT called “News & Movies” exists in the channel 12-2 andchannel ETT called “sports” exists in the channel 12-3. In this case,instances of the two channel ETTs has the same PID (PacketIDentification) and is represented as ETT-V. And, each instance of thechannel ETTs has the same table type, version number, tableidentification and the like.

In the channel 12-1, an event having a title of “Local News” at6:00˜7:00 pm and an event having a title of “Dino World” at 7:00˜9:00 pmexist as broadcast programs. This information is delivered via EIT-0table having the same value of source identification of a virtualchannel 12-1.

In the channel 12-2, an event having a title of “Local News” at6:00˜7:00 pm and an event having a title of “Dino World” at 7:00˜9:00 pmexist as broadcast programs. This information is delivered via EIT-0table having the same value of source identification of a virtualchannel 12-2. In this case, it is exemplarily shown that each of theevents in the channel 12-2 includes a broadcast content message having amore extended content. This is forwarded via event ETT. In the formerevent, event ETT for the event named “Today's headline . . . ” exists.In the latter event, event ETT named “(1997) Harrison Pontiac, PegO'Ryan Dinosaurs eat Newark, N.J. in the Francis Ford Spielbergoscar-winning film” exists.

In the channel 12-3, an event having a title of “Soccer-World Cup” at6:00˜7:30 pm, an event having a title of “Golf” at 7:30˜8:00 pm, and anevent (EIT-0) having a title of “Table Tennis” at 8:00˜9:00 pm exist asbroadcast programs. These events are delivered via EIT-0 table havingthe same value of source identification of a virtual channel 12-3. Inthis case, it is shown that event ETT (event ETT-v) to forward abroadcast content message having an extended content named “Player”exists in the event having the title named “Table Tennis”.

Hence, in FIG. 5, there exist three event ETTs to forward the broadcastcontent messages having the extended contents for several events. Eachof the event ETTs has the same values of PID, version number, tableidentification and table type. As can be seen in FIG. 5, if the numberof the virtual channels is raised, the number of the instances of theduplicative channel ETTs and event ETTs will be increased as well.

As mentioned in the above description of the EPG, the present inventionintends to perform a section-filtering on the numerous duplicativechannel ETTs and event ETTs to receive a non-duplicative ETT section ora specific section only instead of receiving an ETT section duplicativewith a previously received one. In case that a content of the channelETT is changed (e.g., the version number is changed), one channel ETTthat is changed in the above manner can be quickly received.

FIG. 6 illustrates a structure of a database (DB) associated with thepresent invention. Referring to FIG. 6, source identification and eventidentification required for receiving channel ETT and event ETT arestored in a database (DB). The database (DB) shown in FIG. 6 includes apart storing the source identification linking VCT and the channel ETTtogether and a part storing the event identification linking EIT and theevent ETT together.

The source identification, as shown in FIG. 6, is represented as“source_id_(A˜Z)”. In this case, the “A˜Z” corresponds to a virtualchannel to represent the source identification existing in each of thechannels A to Z existing within the VCT. The event identification isrepresented as “event_id_(A1˜An) to (Z1˜Zn)”. In this case, the “A˜Z”corresponds to a virtual channel and the “1˜n” indicates an eventexisting in each of the virtual channels. Namely, it means that an eventcorresponding to A1˜An exists in the virtual channel A.

A process for performing a section-filtering in a manner of filtering aheader of an ETT section received by a receiver according to the presentinvention is explained as follows. As mentioned in the foregoingdescription, there exist channel ETT and event ETT, which will beindividually explained in the following description.

First of all, in performing the section-filtering, a DTV is turned on. Aspecific channel is previously selected in the DTV. A DTV receiverreceives channel information via VCT, PAT (Program Association Table) orPMT (Program Map Table). And, the DTV receiver sets an A/V PID of aspecific virtual channel determined by a viewer to the demultiplexer 30.Hence, the viewer watches the specific virtual channel. In the presentinvention, it is assumed that the viewer requests ETT information of thecurrently watched specific virtual channel. If a request for the ETTinformation is made, a section-filtering is initiated by filtering aheader only according to the present invention.

As mentioned in the foregoing description, the section-filteringincludes one case of receiving a non-duplicative ETT section only bydiscarding an ETT section duplicative with a previously received one andthe other case of receiving a specific ETT section only. Moreover, aconcept of the section-filtering may include a case of combining theformer two cases together. In the following description of the presentinvention, theses three cases will be taken as examples in the presentinvention.

First of all, the case of receiving a non-duplicative ETT section onlyby discarding an ETT section duplicative with a previously received oneis explained as follows. FIG. 7 is a flowchart illustrating a method fordetecting a non-duplicative channel ETT section according to the presentinvention.

Referring to FIG. 7, if a user requests information of ETT, the PSI/PSIPdecoder 80 controls the demultiplexer 30 to perform a section-filteringby a header. Namely, the PSI/PSIP decoder 80 sets a condition for thesection-filtering in the demultiplexer 30. The demultiplexer 30 thenfilters the header according to the set condition. In particular, acorresponding PID is assigned to the audio/video or data service using atable type acquired from the MGT and an ETT section having the assignedPID is received only. In doing so, a condition for receiving a sectionincluding ETT table ID extension field having source identificationrecorded therein only is applied to the received ETT section having metthe former condition.

Thus, the DTV receiver performs the section-filtering through the twoconditions. Hence, the DTV receiver receives the channel ETT sectionthat meets the two conditions only (S10).

The source identification recorded in ETT table ID extension field ofthe channel ETT section, which has met the conditions and is received bythe DTV receiver, is read out. It is then decided whether the read-outsource identification is equal to source identification stored in adatabase (DB). In particular, it is decided whether the sourceidentification recorded in the ETT table ID extension field of thereceived channel ETT section is equal to, i.e., duplicative with thesource identification, which was generated from decoding VCT, stored inthe database (DB) (S20).

As a result of the decision (S20), if the two source identification'sare equal to each other, it is decided that the received channel ETTsection is duplicative with a previously received section. Hence, theduplicative channel ETT section is discarded. And, it goes back to thefirst step to receive a non-duplicative channel ETT section (S30).

As a result of the decision (S20), if the two source identification'sare not equal to each other, it is decided that the received channel ETTsection is a non-duplicative channel ETT section instead of beingduplicative with a previously received section. And, it goes to a nextstep. So, the section-filtering process by the header in thedemultiplexer 30 is completed. Hence, the above-explained steps S10 toS30 correspond to the explanation of the section-filtering by filteringthe header in the demultiplexer 30 controlled by the PSI/PSIP decoder80.

A process for parsing and processing the channel ETT sections receivedthrough the section-filtering is explained as follows. In this case, theparsing is performed by the PSI/PSIP decoder 80.

First of all, as a result of the decision (S20), if the two sourceidentification's are not equal to each other, it is decided that thereceived channel ETT section is not an duplicative channel ETT sectionbut a non-duplicative channel ETT section. The PSI/PSIP decoder 80 thendetects a channel ETT section-out received via the demultiplexer 30(S40). The PSI/PSIP decoder 80 parses a header of the detected channelETT section again (S50).

And, the PSI/PSIP decoder 80 reads out ETM identification, which isactual section data, by parsing a message body of the channel ETTsection (S60). An ETM (extended text message) is then stored in thedatabase (DB) (S70).

Through the above-explained processes, one channel ETT section isprocessed or handled. If there exists another channel ETT section thatis not received yet, the above-explained processes are repeated.

FIG. 8 is a flowchart illustrating a method for detecting a specificchannel ETT section according to the present invention. A process forreceiving a specific channel ETT section is basically identical to theprocess explained in FIG. 7. For convenience of explanation, asection-filtering part different from that of the process of FIG. 7 isexplained only and the rest part will refer to the process of FIG. 7.

First of all, a corresponding PID is assigned to the audio/video or dataservice using a table type acquired from the MGT and an ETT sectionhaving the assigned PID is received only. In doing so, a condition forreceiving a section including ETT table ID extension field having sourceidentification recorded therein only is applied to the received ETTsection having met the former condition. Thus, the DTV receiver performsthe section-filtering through the two conditions. Hence, the DTVreceiver receives the channel ETT section that meets the two conditionsonly (S110).

The source identification recorded in ETT table ID extension field ofthe channel ETT section, which has met the conditions and is received bythe DTV receiver, is read out. It is then decided whether the read-outsource identification is equal to source identification stored in adatabase (DB). In particular, it is decided whether the sourceidentification recorded in the ETT table ID extension field of thereceived channel ETT section is equal to the source identification,which was generated from decoding VCT, stored in the DB (S120).

As a result of the decision (S120), if the two source identification'sare not equal to each other, it is decided that the received channel ETTsection is not a specific channel ETT section. Hence, the receivedchannel ETT section is discarded (S130).

As a result of the decision (S20), if the two source identification'sare equal to each other, it is decided that the received channel ETTsection is the specific channel ETT section. And, it goes to a nextstep. So, the section-filtering process in the demultiplexer 30 iscompleted. A parsing and handling process in the PSI/PSIP decoder 80 isequal to the process explained in FIG. 7, which is invoked in thisdescription. Namely, steps S140 to S170 in FIG. 8 exactly correspond tothe steps S40 to S70 in FIG. 7.

The event ETT is explained in the following description. FIG. 9 is aflowchart illustrating a method for detecting a non-duplicative eventETT section according to the present invention.

Referring to FIG. 9, a corresponding PID is assigned using a table typeacquired from the MGT and an event ETT section having the assigned PIDis received only. In doing so, a condition for receiving a sectionincluding ETT table ID extension field having event identificationrecorded therein only is applied to the received event ETT sectionhaving met the former condition. Thus, the DTV receiver performs thesection-filtering through the two conditions. Hence, the DTV receiverreceives the event ETT section that meets the two conditions only(S210).

The event identification recorded in ETT table ID extension field of theevent ETT section, which has met the conditions and is received by theDTV receiver, is read out. It is then decided whether the read-out eventidentification is equal to event identification stored in a database(DB). In particular, it is decided whether the event identificationrecorded in the ETT table ID extension field of the received event ETTsection is equal to, i.e., duplicative with the event identification,which was generated from decoding VCT, stored in the database (DB)(S220).

As a result of the decision (S220), if the two event identification'sare equal to each other, it is decided that the received event ETTsection is duplicative with a previously received section. Hence, theduplicative event ETT section is discarded. And, it goes back to thefirst step to receive a non-duplicative event ETT section (S230).

As a result of the decision (S220), if the two source identification'sare not equal to each other, it is decided that the received event ETTsection is a non-duplicative event ETT section instead of beingduplicative with a previously received section. And, it goes to a nextstep. So, the section-filtering process in the demultiplexer controlledby the PSI/PSIP decoder 80 is completed. A process for parsing andprocessing the event ETT section received through the section-filteringis explained as follows. In this case, the parsing is performed by thePSI/PSIP decoder 80.

First of all, as a result of the decision (S220), if the two eventidentification's are not equal to each other, it is decided that thereceived event ETT section is not an duplicative event ETT section but anon-duplicative event ETT section. The PSI/PSIP decoder 80 then detectsan event ETT section-out received via the demultiplexer 30 (S240). ThePSI/PSIP decoder 80 parses a header of the detected event ETT sectionagain (S250).

And, the PSI/PSIP decoder 80 reads out ETM identification, which isactual section data, by parsing a message body of the parsed event ETTsection (S260). An ETM (extended text message) is then stored in the DB(S270).

Through the above-explained processes, one event ETT section isprocessed or handled. If there exists another event ETT section that isnot received yet, the above-explained processes are repeated.

FIG. 10 is a flowchart illustrating a method for detecting a specificevent ETT section according to the present invention. A process forreceiving a specific event ETT section is basically identical to theprocess explained in FIG. 9. For convenience of explanation, asection-filtering part different from that of the process of FIG. 9 isexplained only and the rest part will refer to the process of FIG. 9.

First of all, a corresponding PID is assigned using a table typeacquired from the MGT and an event ETT section having the assigned PIDis received only. In doing so, a condition for receiving a sectionincluding ETT table ID extension field having event identificationrecorded therein only is applied to the received event ETT sectionhaving met the former condition. Thus, the DTV receiver performs thesection-filtering through the two conditions. Hence, the DTV receiverreceives the event ETT section that meets the two conditions only(S310).

The event identification recorded in ETT table ID extension field of theevent ETT section, which has met the conditions and is received by theDTV receiver, is read out. It is then decided whether the read-out eventidentification is equal to event identification stored in a database(DB). In particular, it is decided whether the event identificationrecorded in the ETT table ID extension field of the received event ETTsection is equal to the event identification, which was generated fromdecoding VCT, stored in the DB (S320).

As a result of the decision (S320), if the two event identification'sare not equal to each other, it is decided that the received event ETTsection is not a specific event ETT section. Hence, the received eventETT section is discarded. And, it goes back to the first step to receivea specific event ETT section (S330).

As a result of the decision (S320), if the two source identification'sare equal to each other, it is decided that the received event ETTsection is the specific event ETT section. And, it goes to a next step.So, the process for performing the section-filtering in a manner offiltering the header in the demultiplexer 30 controlled by the PSI/PSIPdecoder 80 is completed.

A process for parsing and handling the event ETT section receivedthrough the section-filtering is equal to the process explained in FIG.9. Namely, steps S340 to S370 in FIG. 10 exactly correspond to the stepsS240 to S270 in FIG. 9.

In the above-explained embodiment, the source identification or eventidentification of the specific ETT section is stored in the DB inreceiving the specific channel ETT section or event ETT section. Yet,the present invention does not put limitation on this.

Hence, in performing the section-filtering to receive the specific ETTsection only, the source identification or event identification assignedto the specific ETT section is compared to the other sourceidentification or event identification specified in the ETT table IDextension field of the received ETT section.

Moreover, in performing the section-filtering to receive the specificETT section only, the specific section among the received ETT sectionscan be only received by receiving non-duplicative ETT sections bydiscarding a received section that is not the specific section. Or, inperforming the section-filtering to receive the non-duplicative ETTsection only, the duplicative section(s) among the received ETT sectionscan be discarded. And, the DTV receiver is received the non-duplicativeETT sections only. It can be then decided whether the non-duplicativeETT section is equal to the specific ETT section.

Namely, in case that the received ETT section is not the specific ETTsection in FIG. 10, it can be decided whether the received ETT sectionis the non-duplicative ETT section like FIG. 9. Or in case that thereceived ETT section is the non-duplicative ETT section in FIG. 9, itcan be decided whether the received ETT section is the specific ETTsection like FIG. 10.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A digital television (DTV) receiver for processing a DTV signal, theDTV receiver comprising: a receiving unit for receiving a digitaltelevision signal including a plurality of event extended text table(ETT) instances that appear in transport stream packets with common PIDvalues, the event ETT instances having common table ID values, eachevent ETT instance comprising a section header and a message body, thesection header containing a table identification (ID) field that servesto establish uniqueness of each event ETT instance, the message bodycontaining an extended text message (ETM) which provides detaileddescriptions of a virtual channel or an event associated with each eventETT instance, wherein the header further contains a field indicating asection number which is always set to a predetermined value; ademodulator for demodulating the digital television signal; and anidentifying unit for identifying at least one pertinent event ETTinstance from the plurality of event ETT instances.
 2. The DTV receiverof claim 1, wherein the section number field is a 8-bit field.
 3. TheDTV receiver of claim 1, wherein the table identification extensionfield defines a value indicating an event identifier (ID) associatedwith each event ETT instance.
 4. The DTV receiver of claim 3, whereinthe table identification extension field further defines a valueindicating an ETM location.
 5. The DTV receiver of claim 1, wherein thetable identification extension field has a 16-bit integer value.
 6. TheDTV receiver of claim 1, wherein the plurality of event ETT instancesare section-filtered based on a condition that the at least onepertinent event ETT instance has a specific PID value.
 7. The DTVreceiver of claim 1, wherein the plurality of event ETT instances aresection-filtered based on a condition that the table ID extension fieldincluded in the at least one pertinent event ETT instance includes aspecific value.
 8. The DTV receiver of claim 7, wherein the specificvalue specifies a unique identification number of an event associatedwith the at least one pertinent event ETT instance.
 9. The DTV receiverof claim 8, wherein the plurality of event ETT instances aresection-filtered based on a condition that the table ID extension fieldincluded in the at least one pertinent event ETT instance includes anon-duplicative event identifier.
 10. The DTV receiver of claim 1,further comprising: a parser for parsing the identified at least onepertinent event ETT instance; and a storage for storing an extended textmessage (ETM) included in the parsed event ETT instance.